Methods and apparatus for inserting multi-lumen spit-tip catheters into a blood vessel

ABSTRACT

Methods and apparatus are disclosed for inserting flexible, multi-lumen catheters into blood vessels, and in particular, for inserting flexible, split-tip catheters into blood vessels. The invention accomplishes these objects by temporarily stiffening each catheter lumen and tip independently through use of intra-catheter stiffener elements disposed within the catheter lumens. This provides means for advancing the catheter/stiffeners assembly through a subcutaneous tunnel, and over a plurality of guidewires until a distal tip of the catheter is at a desired position within the vessel. The intra-catheter stiffener elements are sufficiently stiffening to allow advancing the catheter over guidewires, but sufficiently flexible to allow bending and looping of the catheter for proper placement within the vessel.

BACKGROUND OF THE INVENTION

[0001] The invention relates to methods and apparatus for inserting acatheter into a body cavity and, more particularly, though notexclusively, to methods and apparatus for inserting a multi-lumensplit-tip hemodialysis catheter into a blood vessel for hemodialysis.

[0002] Multi-lumen catheters are desirable for various treatmentapplications such as hemodialysis where fluid extraction and infusionoccur simultaneously. These multi-lumen catheters provide a singlecatheter application having multiple lumen channels each supportingindependent flow, thus precluding the need for inserting multiplecatheters or multiple-catheter assemblies. Further, because a patientmight require frequent dialysis, often only days apart, it is desirableto secure placement of the catheter for extended periods of time.Extended placement, however, requires extreme catheter flexibility toavoid damage to the vessel and permit the catheter to move in the bloodflow to minimize the possibility of the catheter remaining in pressurecontact with the wall of the vessel for prolonged periods.

[0003] Unfortunately, the desired flexibility of these catheterspresents insertion difficulties. For example, simply advancing thecatheter over a guidewire is very difficult since the catheter lackssufficient stiffness to slide easily through the vessel wall and intothe blood vessel to the desired location. Flexible catheters presentadditional difficulties associated with subcutaneous tunneling andplacement.

[0004] Known insertion methods and assemblies attempt to overcome, or atleast mitigate, these insertion difficulties by stiffening the cathetertemporarily during the insertion process. For example, one known methodinvolves temporarily inserting a rigid tubular applicator into one ofthe lumens. This permits the stiffened catheter/applicator assembly tobe passed over a guidewire into a desired position, at which point theapplicator can be removed. For example, U.S. Pat. No. 5,405,341 attemptsto solve the problem with a single rigid applicator that is designed forinsertion into one lumen but also passes through a portion of the secondlumen (at the distal end of the instrument) to effectively stiffen thetwo lumens of the catheter together during insertion. This approach iscumbersome, at best, and presents additional difficulties in maneuveringthe instrument. Further, this temporary rigid applicator approach,however, is poorly suited for placement of a catheter having a split atits distal end into two or more separate lumens (e.g., to furtherisolate a fluid extraction lumen from a return infusion lumen) becauseonly one tip can be secured.

[0005] Hence, there exists a need for better and more effective methodsand apparatus for insertion of flexible catheters into vessels.

SUMMARY

[0006] The invention provides methods and apparatus for insertingflexible, multi-lumen catheters into blood vessels, and in particular,for inserting flexible, split-tip catheters into blood vessels. Theinvention accomplishes these objects by temporarily stiffening eachcatheter lumen and tip independently through use of intra-catheterstiffener elements disposed within the catheter lumens. This providesmeans for advancing the catheter/stiffeners assembly through asubcutaneous tunnel, and over a plurality of guidewires until a distalportion of the catheter is at a desired position within the vessel.

[0007] The intra-catheter stiffener elements are sufficiently stiffeningto allow advancing the catheter over guidewires, but also sufficientlyflexible to allow bending and looping of the catheter for properplacement within the vessel. Further, the intra-catheter stiffenerelements prevent catheter kinking during the insertion process. In oneembodiment, the intra-catheter stiffener elements have tapered distalends which can facilitate entry of the catheter/stiffeners assembly intoa blood vessel and/or assist in dilating the blood vessel.

[0008] One aspect of the invention provides methods and apparatus forinserting an antegrade tunneled, split-tip, hemodialysis catheter into ablood vessel. A distal portion of each of a plurality of guidewires isdisposed in a blood vessel at a first location, generally in proximityto the vessel in which a portion of the catheter is to be placed. Asubcutaneous tunnel is formed between the first location and a secondlocation where a proximal end of the catheter can extend from thepatient. An intra-catheter stiffener element is inserted into theproximal end of each catheter lumen until it extends beyond the distalend of that catheter lumen. The intra-catheter stiffener element can bereleasably coupled, following insertion, to the proximal end of itsrespective catheter lumen via, for example, a mating luer assembly. Eachguidewire can be inserted into to a distal end of a lumen in arespective intra-catheter stiffener element until that guidewire extendsfrom the proximal end of that intra-catheter stiffener element. Thecatheter can then be advanced over the guidewires and into the bloodvessel. Alternatively, the catheter can be advanced over the guidewiresuntil a distal end of the catheter is adjacent to the vessel, at whichpoint the catheter and guidewires can be advanced together into thevessel until the distal end of the catheter is at a desired locationtherein. Twisting the catheter while simultaneously advancing it alongthe guidewires can facilitate placement of the catheter into the vessel.

[0009] In another aspect, the methods and apparatus of the inventionprovide for inserting a retrograde tunneled hemodialysis catheter into ablood vessel. A distal portion of each of a plurality of guidewires isinserted into a blood vessel at a first location generally as describedabove. An intra-catheter stiffener element is placed in each catheterlumen until it extends from a distal end of the catheter, and can bereleasably connected to the proximal end of its respective catheterlumen, as noted above. A proximal end of each guidewire is threadedthrough the distal end of a lumen of each intra-catheter stiffenerelement until the guidewire extends beyond the proximal end of thatstiffener element. The catheter is advanced over the guidewires,optionally using a twisting motion, until a distal portion of thecatheter is disposed at a desired location within the vessel, oralternatively, the catheter can be advanced until its distal end isadjacent to the vessel, at which point the catheter and guidewires canbe advanced together until the distal end of the catheter is disposed ata desired location within the vessel. The guidewires are removed fromthe catheter lumens. A subcutaneous tunnel is then formed between thefirst location and a second location, and the proximal end of thecatheter is passed through the first location until it extends from thesecond location. (If the stiffener elements have not previously beenremoved, they can be removed from the catheter body following passage ofthe catheter through the tunnel.) An access port is connected to theproximal end of each of the catheter lumens allowing fluid connectionwith a treatment device, such as a hemodialysis infuser.

[0010] In a related aspect, the methods and kits of the presentinvention can provide for dilating the desired vessel subsequent toinserting the distal portion of a first guidewire. For example, a size6-French sheath/dilator can be threaded over the first guidewire.Further guidewires can then be inserted into the expanded vessel, orthrough a lumen in the sheath and into the vessel. After placement ofthe guidewires into the vessel, the dilator or sheath can be removed.

[0011] In a further related aspect, the methods provide for tunnelingbetween the first and second location by using a pointed stylet. Adistal end of a pointed stylet can be inserted through the skin at thesecond location and pushed toward the first location until the distalend extends therefrom. The distal end of the catheter is removablyattached to a proximal end of the stylet. The stylet is then pulled fromthe first location until the distal end of the catheter extendstherefrom, to facilitate an antegrade tunneled catheter.

[0012] Alternatively, a pointed distal end of a stylet can be insertedthrough the skin at the first location and pushed until it extends fromthe second location. The proximal end of the catheter can be removablyattached to the proximal end of the stylet. The stylet is then pulledback toward the second location until the proximal end of the catheterextends therefrom. The catheter is then released from the stylet, thuspositioning a retrograde tunneled catheter. To facilitate movement ofthe catheter within the tunnel, the proximal end of the catheter havingmating lures or other coupling features can be removed or severed priorto attachment to the stylet. After tunneling the catheter, fluidcouplings or other attachments can be disposed to the proximal end ofthe lumens.

[0013] Preferably, the vessel is expanded to accommodate placement ofthe distal portion of the catheter in the vessel. Vessel dilators ofincreasing size can be sequentially inserted into the vessel for thispurpose. For example, a size 12-French dilator followed by a size14-French, which is then followed by a size 16-French dilator, can beinserted into the vessel before advancing the catheter along theguidewires. In other embodiments, fewer (or more) dilators of differentsizes can be used. Differing size and number of vessel dilators can beused corresponding to the catheter chosen for the desired application.Use of intra-catheter stiffener elements can preclude use of vesseldilators sized larger that the catheter since the stiffener elements andthe catheter itself can provide vessel dilation.

[0014] Another aspect of the invention provides for apparatus, in theform of a kit, to insert a multi-lumen catheter into a blood vessel. Thekit comprises guidewires each adapted to have a distal portion insertedinto a blood vessel. A plurality of intra-catheter stiffener elementspreferably having tapered distal ends are also provided, each having alumen extending along its length sized to accommodate a guidewire, andeach having an outside diameter sized to be slidably disposed within alumen of the catheter. The intra-catheter stiffener elements can beprovided in one or more predetermined lengths corresponding to a lengthof a catheter and its lumens selected for a particular use, or can be ofthe same length. Further, the intra-catheter stiffeners can be providedwith mating devices, such as lures, disposed at a proximal endcorrespond with mating connectors disposed at a proximal end of thecatheter lumens.

[0015] One or more vessel dilators can also be provided in the kit, eachcorresponding in size to a particular application. For example, a size6-French sheath/dilator can be provided to dilate the vessel toaccommodate a plurality of guidewires. A size 12-French, 14-French, aswell as a size 16-French, dilator can be provided to dilate the vesselto accommodate the distal tip of the catheter.

[0016] The present invention is applicable in the field of hemodialysis,among others, for inserting a multi-tip catheter into a blood vessel.The methods and apparatus provide for insertion of a split-tip catheterwithout using a tearable sheath and avoid the problems associated withprior art approaches of split tip catheter insertion over a singleguidewire.

BRIEF DESCRIPTION OF THE INVENTION

[0017] These and other objects, advantages and features of the presentinvention will be readily appreciated as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, in which likereference numerals designate like parts throughout the figures thereofand wherein:

[0018]FIG. 1 is a schematic, partially cutaway, side view of ahemodialysis catheter insertion system according to the invention;

[0019]FIG. 2 is a schematic illustration of an initial step of a methodaccording to the invention in which a distal portion of a firstguidewire is inserted in a vessel;

[0020]FIG. 3 is a schematic illustration of another step of the methodof the invention in which a blood vessel dilating sheath and a distalportion of a second guidewire are inserted in a vessel;

[0021]FIG. 4 is a schematic illustration of another step of the methodin which an antegrade catheter is disposed in a subcutaneous tunnelbetween a first location and a second location according to theinvention;

[0022]FIG. 5 is a schematic illustration of another step of the methodin which the first guidewire is threaded through a first lumen of acatheter assembly according to the invention, in which the catheterassembly has an intra-catheter stiffener element disposed in each lumenof the catheter;

[0023]FIG. 6 is a schematic illustration of another step of the methodin which the second guidewire is threaded through the second lumen ofthe catheter assembly to a point where two loops of guidewire remain tofacilitate placement of the distal end of the catheter in the vessel;

[0024]FIG. 7 is a schematic illustration of another step of the methodin which the catheter assembly has been advanced along the guidewiresuntil the distal portion of the catheter is positioned within the vesselat a desired location;

[0025]FIG. 8 shows the catheter of FIG. 7 with the intra-catheterstiffener elements and guidewires removed;

[0026]FIG. 9 is a schematic illustration showing a step of a methodaccording to the invention wherein a retrograde catheter is shown havinga distal end disposed in a vessel;

[0027]FIG. 10 is a schematic illustration showing a further step of themethod wherein the catheter has been subcutaneously tunneled subsequent;

[0028]FIG. 11 shows the catheter with fluid-couplers installed; and

[0029]FIG. 12 shows a kit according to the invention for installingcatheters such as those described above.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In FIG. 1 a catheter system 10 according to the invention isshown having a catheter body 12 with two internal lumens 14A and 14B.The catheter body 12 has a “split-tip” distal end 16 in which the body(and lumens) separate into two distal tip portions, 18A and 18B. Thesplit tips can, but need not have one or more side ports 20A and 20B, influid communication with one or the other of the lumens to facilitateblood removal and return, respectively, during hemodialysis.Alternatively, or in conjunction with side ports, the distal ends can beopen to provide fluid passageways for blood removal and return. Theproximal end 22 of the catheter body can also be split into separatesegments 22A and 22B and terminates with two access ports 28A and 28B,which can include couplings, such luer-locks or the like, to couple thecatheter to a hemodialysis machine in which blood is circulated andpurified. The overall system or kit of the invention can also includetwo intra-catheter stiffener elements 24A and 24B and two guidewires 26Aand 26B (shown within the respective lumens 14A and 14B). The catheterbody 12 is typically a very flexible silicone, polyurethane or otherbiocompatible composition (e.g., having a stiffness in the range ofabout 65 to about 85 durometers). Preferably, the intra-catheterstiffener elements 24A and 24B are composed of a stiffer form ofpolyethylene or other biocompatible material. In addition to stiffeningthe assembly, the stiffener elements can also help to prevent kinking ofthe catheter during insertion.

[0031] The catheter system 10 of FIG. 1 provides for insertion of thedistal end of the multi-lumen, split-tip, flexible catheter body 12 intoa blood vessel using the intra-catheter stiffener elements andguidewires, as will be explained below. Briefly, a distal portion ofeach guidewire is disposed at a desired position within the vessel. Anintra-catheter stiffener element having a tapered tip to facilitateinsertion into the vessel and to provide catheter stiffening is slidablydisposed along the length of each catheter lumen until it extends beyondthe distal tip of that catheter lumen. A proximal end of each guidewireis threaded through a distal end of a lumen extending along each of theintra-catheter stiffener elements. The catheter is then advanced overthe guidewires and into the blood vessel. Alternatively, the cathetercan be advanced over the guidewires until the distal end is adjacent tothe vessel, at which point the catheter and guidewires can be advancedtogether into the blood vessel. The guidewires and intra-catheterstiffener elements are then removed from the catheter. The methods andapplication kit described can be used for any split-tip catheter, andare particularly useful for insertion of subcutaneously tunneledhemodialysis catheters.

[0032] A method of insertion according to the invention will next bedescribed in connection with FIGS. 2-8. The procedure involves not onlyinserting the catheter tips into a blood vessel but also forming asubcutaneous tunnel below a patient's skin to secure the catheter inplace and is sometimes described as antegrade or forward insertion. Itwill be appreciated, however, that the methods described herein can beused for inserting catheter tips into a blood vessel where tunneling isnot necessary or desired.

[0033]FIG. 2 schematically shows an initial step of a method accordingto the invention in which a distal portion of a first guidewire 26A isinserted in a vessel 4 of a patient 2. The entry location 6 of theguidewire 26A is referred to herein as the “first location” or the“venotomy site.” This first location is typically a surgical incisionthat provides access to the desired blood vessel which typicallyincludes the internal or external jugular, femoral or subclavian vein,and the vena cava, for example. In one preferred embodiment, the bloodvessel chosen for catheter placement can be the right side internaljugular vein.

[0034] In FIG. 3, a blood vessel sheath/dilator 30 is shown insertedover the first guidewire 26A to dilate the vessel. The distal portion ofa second guidewire 26B is then inserted in the vessel 4 via thesheath/dilator 30.

[0035] With reference to FIG. 4, a subcutaneous tunnel 40 is formed(before or after the insertion of guidewires 26A and 26B) to anchor thecatheter body in place and provide two remote ports for coupling the twolumens of the catheter to a dialysis machine. In FIG. 4, a catheter body12 of an antegrade catheter has been disposed in a subcutaneous tunnel40 between the first (venous access) location 6 and a second (exit)location 32, such that the distal end of the instrument including thesplit tips 18A and 18B extend from the first location. Prior toinsertion, each of the lumens of catheter body 12 has been fitted with ahollow, tubular, intra-catheter stiffener element or liner, 24A and 24B,respectively.

[0036] In FIG. 5, the first guidewire 26A is threaded through a firstlumen of the catheter assembly (i.e., through the lumen ofintra-catheter stiffener element 24A). In FIG. 6, the second guidewire26B is threaded through the second lumen of the catheter assembly (i.e.,through the lumen of intra-catheter stiffener element 24B). Each of theguidewires is advanced through the catheter assembly to a point wheretwo short loops of guidewire remain to facilitate placement in thevessel.

[0037] As shown in FIG. 7, the catheter assembly is then advanced alongthe guidewires until the distal end 16 of the catheter is positioned ata desired position within the vessel. In a preferred embodiment, thecatheter is advanced over the guidewires until the distal end isadjacent to the vessel, and then the catheter and the guidewires can beadvanced together until the distal end of the catheter is positioned ata desired position within the vessel. The guidewires 26A and 26B canthen be removed by withdrawing them via the proximal end 22 of thecatheter body. Likewise, the intra-catheter stiffener elements 24A and24B can be removed (either subsequent to the guidewires or at the sametime).

[0038] Advantageously, this method precludes using a vessel dilatorlarger than the catheter/stiffeners assembly for placement of thecatheter within the vessel since the intra-catheter stiffener elementsand the catheter itself provide vessel dilation.

[0039]FIG. 8 shows the catheter of FIG. 7 with the intra-catheterstiffener elements and guidewires removed. The venous access incision isthen closed and the catheter is secured subcutaneously (e.g., via animplanted cuff and/or sutures).

[0040] Although the above detailed description has been presented inconnection with an antegrade insertion, it should be clear that themethods and systems of the present invention are equally useful inretrograde or reverse insertions (where the catheter body is passedthrough the subcutaneous tunnel from venotomy site to the remote exitlocation).

[0041] Thus, a method according to the invention for insertion of aretrograde catheter will next be described. An initial step forinsertion of a retrograde catheter begins with placement of guidewireswithin the vessel as described above in connection with FIGS. 2 and 3.

[0042]FIG. 9 illustrates a step of the method wherein the catheter body12 has each of the lumens fitted with a hollow, tubular, intra-catheterstiffener element or liner, 24A and 24B, respectively. Theintra-catheter stiffener elements can have a coupler at a proximal endthat releasably couple to a mating coupler at a proximal end of therespective catheter lumen. Guidewires 26A and 26B are threaded throughthe lumens of the catheter assembly as described above in FIGS. 5 and 6.The catheter body is advanced along the guidewires until the distal endof the catheter in a desired location within the vessel. Alternatively,the catheter body can be advanced along the guidewires until the distalend is adjacent to the vessel, and then the catheter and the guidewirescan be advanced until the distal end is located at a desired positionwithin the vessel. The guidewires and, optionally, the intra-catheterstiffener elements are then removed from the lumens.

[0043]FIG. 10 shows a step of the method wherein the catheter has beensubcutaneously tunneled. A subcutaneous tunnel is formed between asecond location 32 (exit location) and the first location 6 (venotomysite). Couplers at the proximal end 22 of the catheter lumens areremoved, or alternatively, severed therefrom to allow the proximal endof the catheter to be pulled through the tunnel 40. In one embodiment,the proximal end of the catheter is pulled through subcutaneous tunnelfrom the first location until it extends from the second location.

[0044]FIG. 11 illustrates the catheter after tunneling with access ports28A and 28B installed, or alternatively, replaced and ready to becoupled to a hemodialysis machine for blood purification.

[0045] As noted above, it will be appreciated that the use of theintra-catheter stiffener elements provide sufficient stiffness so thatthe flexible split tips can be slid over the guidewires into the desiredposition with less effort and reduced likelihood of trauma. Catheterkinking is mitigated during the insertion process, thus reducingcomplexity of catheter insertion.

[0046]FIG. 12 shows contents of a preferred embodiment of a kit 48providing equipment to perform the above described methods. Illustratedare two intra-catheter stiffener elements 50A and 50B, two guidewires52A and 52B, a 6-French sheath/dilator 54 and two vessel dilators ofdiffering sizes 56 and 58. It will be appreciated by one skilled in theart that other arrangements are contemplated, each having at least twointra-catheter stiffener elements. For example, in one embodiment, theinsertion kit has a split-tip catheter and two intra-catheter stiffenerelements. The kit is suitable for insertion of either antegrade orretrograde catheter configurations according to the illustrated methodsdescribed above.

[0047] Intra-catheter stiffener elements 50A and 50B are illustrated as5-French in size and of the same length. However, intra-catheterstiffener elements 50 need not be of the same size and length, but canbe selected according to the size and length of the catheter to beinserted. Further, intra-catheter stiffener elements need not have around exterior shape, but rather, can have an external shape accordingto the size and shape of an interior of a catheter lumen, for example,oval shaped. In a preferred embodiment, each intra-catheter stiffenerelement has a tapered configuration along a distal portion to aid indilating the catheter lumen, with a releasable coupler at a proximal endsuch as a luer-coupler at a proximal end. Each has a hollow bore orlumen running along its length sized to slidably receive a guidewire asdescribed above. Each preferably has stiffness sufficient to prevent thecatheter from kinking or otherwise distorting during the insertionprocedure. It will be appreciated that the intra-catheter stiffenerelements can be in kit form as separate from, or disposed within, thecatheter lumens.

[0048] Guidewires 52A and 52B are illustrated as J-straight 0.038″guidewires, however each can vary according to the application andcatheter configuration. Each can have a removable sheath to accommodatehandling and facilitate placement within a desired location such as avein.

[0049] Sheath/dilator 54 is illustrated as size 6-French, however, othersizes may be used to puncture a wall of a vessel and accommodate one ormore guidewires. Dilators 56 and 58 are illustrated as size 14-Frenchand 16-French, respectively, and are suitable for many catheterinsertion procedures. In a preferred embodiment, a size 12-French isprovided in addition to or instead of one of the illustrated dilators.

[0050] It will be appreciated, therefore, that the above methods andkits are useful for inserting hemodialysis catheters in a patient, andin general for multi-lumen split-tip catheters intended for otherfunctions where body fluids are extracted and introduced. As such, theinvention is not limited to those embodiments described above, butrather, is limited by the claims that follow.

What is claimed is:
 1. A method for inserting a multi-lumen catheterinto a blood vessel comprising: inserting a distal portion of each of aplurality of guidewires into a vessel at a first location; inserting anintra-catheter stiffening element into a proximal end of each lumen of amulti-lumen catheter, the catheter having a distal portion for placementin the vessel and a proximal end for connection to a treatment deviceand further having a plurality of lumens; threading a proximal end ofeach of the guidewires through a distal end of a respectiveintra-catheter stiffening element until said guidewire exits theproximal end of the catheter; advancing the catheter into a desiredlocation within the vessel; and removing each of the guidewires and eachof the intra-catheter stiffener elements from the lumens of thecatheter.
 2. The method of claim 1, wherein advancing the catheter intoa desired location within the vessel further comprises: advancing thecatheter over the guidewires until a distal end of the catheter isadjacent to the vessel; and further advancing the catheter and theguidewires into the vessel until the distal portion of the catheter isat the desired location within the vessel.
 3. The method of claim 1,further comprising dilating the blood vessel subsequent to inserting afirst guidewire.
 4. The method of claim 3, further comprising dilatingthe blood vessel using a size 6-French sheath/dilator.
 5. The method ofclaim 1, further comprising coupling a proximal end of each said intra-catheter stiffening element to a proximal end of a respective catheterlumen.
 6. The method of claim 1, wherein the step of advancing thecatheter into a desired location within the vessel comprises twistingthe catheter while advancing.
 7. The method of claim 1, wherein thecatheter has a split-tip.
 8. A method for inserting a multi-lumencatheter into a blood vessel comprising: inserting a distal portion ofeach of a plurality of guidewires into a vessel at a first location;forming a subcutaneous tunnel between the first location and a secondlocation; passing a catheter through the tunnel, the catheter having adistal portion for placement in the vessel and a proximal end forconnection to a treatment device and further having a plurality oflumens; inserting an intra-catheter stiffener element into the proximalend of each of the catheter lumens; threading a proximal end of each ofthe guidewires through a distal end of a respective intra-catheterstiffener element until said guidewire exits the proximal end of thecatheter; advancing the catheter into a desired location within thevessel; and removing each of the guidewires and each of theintra-catheter stiffener elements from the lumens of the catheter. 9.The method of claim 8, wherein advancing the catheter into a desiredlocation within the vessel further comprises: advancing the catheterover the guidewires until a distal end of the catheter is adjacent tothe vessel; and further advancing the catheter and the guidewires intothe vessel until the distal portion of the catheter is at the desiredlocation within the vessel.
 10. The method of claim 8, furthercomprising dilating the blood vessel subsequent to inserting a firstguidewire.
 11. The method of claim 10, further comprising dilating theblood vessel using a size 6-French sheath/dilator.
 12. The method ofclaim 8, wherein forming a subcutaneous tunnel further comprisesinserting a distal end of a pointed stylet through the skin at thesecond location; and pushing the stylet toward the first location untilthe distal end of the stylet extends therefrom.
 13. The method of claim12, wherein the step of passing a catheter through the tunnel furthercomprises: removeably attaching the distal end of the catheter to theproximal end of a stylet; pulling the stylet toward the first locationuntil the distal end of the catheter extends therefrom; and releasingthe catheter from the stylet.
 14. The method of claim 12, wherein thestylet has a shape adapted to tunnel through subcutaneous tissue. 15.The method of claim 8, wherein each intra-catheter stiffener element isinserted into the catheter prior to passage of the catheter through thetunnel.
 16. The method of claim 8, wherein each intra-catheter stiffenerelement is inserted into the catheter after passage of the catheterthrough the tunnel.
 17. The method of claim 8, wherein the proximal endof each catheter lumen has a coupler adapted to mate with a couplerdisposed at the proximal end of an intra-catheter stiffener element. 18.The method of claim 8, further comprising dilating the vessel toaccommodate the distal portion of the catheter.
 19. The method of claim18, further comprising: dilating the vessel with a first dilator; anddilating the vessel with at least one larger further dilator.
 20. Themethod of claim 19, wherein the larger further dilators are adapted todilate the vessel to slidably receive the distal portion of the catheterhaving each catheter lumen stiffened by a respective intra-catheterstiffener element disposed therein.
 21. The method of claim 19, whereinthe first dilator is a size 12-French dilator.
 22. The method of claim19, wherein the further dilators are any of the group consisting of asize 14-French and a 16-French dilator.
 23. The method of claim 8,wherein the step of advancing the catheter further comprises looping thecatheter between the first location and the vessel so as to facilitateadvancing the distal portion of the catheter into the vessel.
 24. Themethod of claim 23, further comprising pulling the proximal end of thecatheter to remove the loop subsequent to advancing the distal portionof the catheter into the vessel.
 25. The method of claim 8, wherein thestep of advancing the catheter further comprises twisting the catheterto facilitate advancement of the distal portion of the catheter to thedesired location within the vessel.
 26. The method of claim 8, furthercomprising coupling the catheter to a hemodialysis treatment device. 27.The method of claim 26, wherein the catheter is a dual-lumen antegradetunneled hemodialysis catheter.
 28. A method for inserting a multi-lumencatheter into a blood vessel comprising: inserting a distal portion ofeach of a plurality of guidewires into a vessel at a first location;placing intra-catheter stiffener elements into each lumen of amulti-lumen catheter; threading a proximal end of each of the guidewiresthrough a distal end of a respective intra-catheter stiffener elementdisposed within the catheter lumen until said guidewire exits a proximalend of the intra-catheter stiffener element; advancing the catheter intoa desired location within the vessel; removing each of the guidewiresand each of the intra-catheter stiffener elements from the lumens of thecatheter; forming a subcutaneous tunnel between the first location and asecond location; passing the catheter through the tunnel; and connectingan adapter to a proximal end of each of the catheter lumens, the adapterconfigured to connect to a treatment device.
 29. The method of claim 28,wherein advancing the catheter into a desired location within the vesselcomprises advancing the catheter over the guidewires until the distalend of the catheter is adjacent to the vessel; and further advancing thecatheter and the guidewires into the vessel until the distal end of thecatheter is at the desired location within the vessel.
 30. The method ofclaim 28, further comprising dilating the blood vessel subsequent toinserting a first guidewire.
 31. The method of claim 30, furthercomprising dilating the blood vessel using a size 6-Frenchsheath/dilator.
 32. The method of claim 28, wherein forming asubcutaneous tunnel further comprises: inserting a distal end of apointed stylet through the skin at the first location; and pushing thestylet toward the second location until the distal end of the styletextends therefrom.
 33. The method of claim 28, wherein the step ofpassing a catheter through the tunnel further comprises: removeablyattaching the proximal end of the catheter to the proximal end of astylet; pulling the stylet back toward the second location until theproximal end of the catheter extends therefrom; and releasing thecatheter from the stylet.
 34. The method of claim 33, wherein the distalend of the stylet has a sharpened point adapted to tunnel throughsubcutaneous tissue.
 35. The method of claim 33, wherein the proximalend of the stylet has a feature adapted to removably affix the proximalend of the catheter.
 36. The method of claim 28, wherein eachintra-catheter stiffener element releasably attaches to the proximal endof its respective catheter lumen.
 37. The method of claim 36, whereineach intra-catheter stiffener element stiffens its respective catheterlumen.
 38. The method of claim 36, wherein the proximal end of eachcatheter lumen has a removable coupler adapted to mate with a couplerdisposed at the proximal end of an intra-catheter stiffener element. 39.The method of claim 28, further comprising dilating the vessel toaccommodate the distal portion of the catheter.
 40. The method of claim39, further comprising: dilating the vessel with a first dilator; anddilating the vessel with at least one larger further dilator.
 41. Themethod of claim 40, wherein the larger further dilators are adapted todilate the vessel to slidably receive the distal portion of the catheterhaving each catheter lumen stiffened by a respective intra-catheterstiffener element disposed therein.
 42. The method of claim 40, whereinthe first dilator is a size 12-French dilator.
 43. The method of claim40, wherein the further dilators are any of the group consisting of asize 14-French and 16-French dilator.
 44. The method of claim 28,further comprising coupling the catheter to a hemodialysis device. 45.The method of claim 44, wherein the catheter is a dual-lumen retrogradetunneled hemodialysis catheter.
 46. A kit for applying a multi-lumencatheter into a blood vessel comprising: a plurality of guidewires, eachadapted to have a distal portion inserted in a blood vessel; and aplurality of intra-catheter stiffener elements, each of theintra-catheter stiffener elements sized to be slidably disposed within alumen of a multi-lumen catheter and each having a lumen sized to slideover a guidewire.
 47. The kit of claim 46, further comprising a vesseldilator adapted to be advanced into the blood vessel over a firstinserted guidewire, the vessel dilator sized to dilate the blood vesselto accommodate insertion of further ones of the guidewires.
 48. The kitof claim 47, wherein the vessel dilator is a size 6-Frenchsheath/dilator.
 49. The kit of claim 49, further comprising at least onefurther vessel dilator sized to dilate a blood vessel to accommodateinsertion of a catheter.
 50. The kit of claim 49, wherein the furthervessel dilators are any size of the group consisting of size 12-French,14-French and 16-French.
 51. The kit of claim 46, wherein theintra-catheter stiffener elements have a tapered distal portion.
 52. Thekit of claim 46, wherein each intra-catheter stiffener element has acoupler disposed at a proximal end adapted to releasably couple to acoupler disposed at the proximal end of a respective catheter lumen. 53.The kit of claim 52, wherein the intra-catheter stiffener elements arereleasably coupled to a proximal end of the catheter lumens.
 54. The kitof claim 52, wherein the intra-catheter stiffener elements have apredefined length corresponding to a length of a catheter selected foruse in a particular application.
 55. The kit of claim 54, wherein thecatheter is a hemodialysis catheter.
 56. The kit of claim 46, furthercomprising a multi-lumen catheter.
 57. The kit of claim 56, wherein theintra-catheter stiffener elements are pre-disposed within the lumens ofthe catheter.
 58. A kit for applying a multi-lumen catheter into a bloodvessel comprising: a multi-lumen catheter comprising a distal portion tobe placed in a blood vessel and a coupler disposed at a proximal end ofeach catheter lumen; and a plurality of intra-catheter stiffenerelements, each of the intra-catheter stiffener elements sized to beslidably disposed within a lumen of the catheter and each having a lumensized to slide over a guidewire, the intra-catheter stiffener elementshaving a tapered distal portion and a proximal end having a coupleradapted to mate with the coupler at the proximal end of a catheterlumen.
 59. The kit of claim 58, further comprising a vessel dilatoradapted to be advanced into the blood vessel over a first insertedguidewire, the vessel dilator sized to dilate the blood vessel toaccommodate insertion of further ones of the guidewires.
 60. The kit ofclaim 59, wherein the vessel dilator is a size 6-French sheath/dilator.61. The kit of claim 60, further comprising at least one further vesseldilator sized to dilate a blood vessel to accommodate insertion of acatheter.
 62. The kit of claim 61, wherein the further vessel dilatorsare any size of the group consisting of 12-French, 14-French and16-French.
 63. The kit of claim 58, wherein the intra-catheter stiffenerelements have a predefined length corresponding to a length of thecatheter selected.
 64. The kit of claim 58, wherein the intra-catheterstiffener elements have an exterior shape sized to be received by aninterior shape of the catheter lumens.
 65. The kit of claim 58, whereinthe intra-catheter stiffener elements are pre-disposed within the lumensof the catheter.
 66. The kit of claim 58, wherein the catheter is ahemodialysis catheter.
 67. The kit of claim 58, wherein the distalportion of the catheter has a split-tip.